In Synchronous Optical Network (SONET) technologies and Synchronous Digital Hierarchy (SDH) technologies in the field of transmission, according to requirements of physical layer protocols, consecutive all zeros or ones should not occur in a data transmission signal because no synchronous clock can be extracted from the consecutive all zeros or ones. In order to prevent occurrence of such phenomena in the signal, a scrambling code technology has been adopted in the industry, which principle is to randomize digit bits in the signal to prevent consecutive all zeros or ones from occurring in the signal.
Currently, the International Telecommunication Union (ITU) specifies two scrambling code technologies which adopt two respective scrambling code algorithms.
One algorithm is a scrambling code technology specified in the GR-253 standards, in which digit bits in a synchronous head of a data frame are scrambled in accordance with an algorithm of 1+x6+x7. In this technology, the scrambling function takes effect all the time and may not be disabled, so the scrambling configurations of the two ends are consistent all the time.
The other algorithm is a scrambling code technology specified in the I.432 standards, in which a scrambling formula of the type of Asynchronous Transfer Mode (ATM) is specified and digit bits in a synchronous head of a data frame are scrambled in accordance with a polynomial algorithm of 1+x43. In this technology, it is not necessary for a transmitting end to inform a receiving end about whether a scrambling is required. The scrambling function is configurable, that is, it can be enabled or disabled through configuration, and therefore the scrambling configurations of both parties of a link connection using this technology may possibly be inconsistent.
In order to ensure a correct transmission and reception of data, it is required in a link using the scrambling code technology that the scrambling configurations of the transmitting end and the receiving end should be consistent, that is, when one of two parities connected through the link configures the scrambling function as “Enabled”, the other shall also configure the scrambling as “Enabled”, otherwise, when all data sent from the transmitting end is scrambled, if the receiving end does not configure the scrambling function as “Enabled”, it can not identify received data, or if the transmitting end does not configure the scrambling function as “Enabled” while the receiving end does, the receiving end can not identify the received date either. Consequently, in practical applications, the use of the above scrambling technology in the I.432 standards may be faced with the issue of detecting consistency of link scrambling configurations.
At present, the above scrambling configurations at the transmitting end and the receiving end are generally accomplished manually, and the consistency of scrambling configurations at both ends of a link is also detected manually. That is, the receiving end has to manually obtain the scrambling configurations of devices at the opposite ends to determine consistency of the scrambling configurations at the two ends. This may give rise to certain problems in practical applications. For example, when devices from two operators are docked, in order for the receiving end to learn about the scrambling configuration at the opposite end, it is required to manually detect whether the scrambling configurations of both parties are consistent, which is not convenient in terms of operations and maintenance. Furthermore, when the device at one end modifies its scrambling configuration during normal operation without informing a device at the opposite end, the device at the opposite end can not receive correct data packets, and therefore normal communications are affected, and if consistency of the scrambling configurations at the two ends is detected through human intervention, operations and maintenance are still time consuming, laborious and inconvenient.